Legacy GT:Subaru Legacy (fourth generation)/DIYs/KONI "Cut-a-Strut" insert install walk-through

From Legacy GT

Overview

KONI is a manufacturer of performance and adjustable shocks. KONI manufacturers a "Cut-a-strut" system that allows you to reuse stock struts (for the front) to create a full shock absorber. This walk-through is a guide for how to properly cut and install a KONI Sport Shock for your Legacy GT.

Original Content

Content Replicated from

Prerequisites

Materials needed

  • A pair of front struts. (20310A Right, Front; 20310B Left, Front)
  • KONI Sport Cartridge (2x fronts 8610-1447SPORT; 2x Rear 8010-1053SPORT)
  • OEM dust cover (FRONT P/N 20322AG00A, qty.1/side; REAR P/N 20372AE00A, qty.1/side)
  • OEM top mount (FRONT P/N 20320AG00A, qty.1/side; REAR P/N 20370AG00A, qty.1/side)
  • Nut & Lock-washer from Koni kit
  • OEM bump stop (P/N 20321AA201, qty.1/side)
  • OEM conical washer (P/N 20326AA000, qty.1/side)
  • OEM upper spring seat (FRONT P/N 20323AG00A, qty.1/side; REAR P/N 20375AE00A, qty.1/side)
  • Springs (Stock or aftermarket)
  • Lower spring perch from Koni kit

Tools needed

  1. Gloves
  2. Safety glasses
  3. Hammer
  4. Center punch
  5. Drill
  6. 1/8" or 3mm drill bit
  7. 1/2" or 12-13mm bit
  8. Tape
  9. Round file (less than 1/2")
  10. Small flat file
  11. Hacksaw or Pipe cutter (Typical product that cuts 5/8 to 2 1/8" OD)
  12. Bench vise
  13. Marking pen
  14. Tape measure
  15. 5/16" hex key
  16. Something to catch used oil
  17. Thread locker
  18. Paper towels

Steps

Cutting the stock strut assembly and inserting the KONI strut

  1. Remove factory strut assembly from the vehicle and remove upper strut mount and spring per factory workshop manual. Place the factory strut upside down in a vise.
  2. Using a tape measure on the bottom of the strut find the exact center of the bottom of the tube and place a mark there with a marking pen.
  3. Make a punch in the center at the mark from Step 2 with a centering punch.
  4. Using an electric drill and a 3 mm (approximately 1/8”) bit drill a hole in the bottom of the strut at the punch mark. Be cautious as some gas and oil may escape out of the hole during this process.
  5. When the gas pressure has escaped, place tape over the bottom hole to reduce spillage.
  6. Using a tape measure or ruler on the NEW KONI insert measure the distance from the bumps on the body to the top of the body (where the chrome rod come out). Write down this measurement. Subtract 7mm (about 1/4 “) from this measurement. Then, using the calculated value, measure down the distance from the top of the original strut to that calculated value and mark a line around the factory strut.
  7. Cut off the tubing at the line using all proper precautions for the cutting tool. You only need to cut the outer tube and not all the way through the strut. Remember the strut still contains oil inside.
  8. Drain the damper and dispose of the oil properly. Remove any burrs from the cut strut tube using a file or other tools available to you. Make sure that when finished the inside edge of the strut tube is smooth.
  9. Enlarge the hole on the bottom to 14mm (approximately 9/16”) using an electric drill. Remove any burrs from the hole.
  10. If there are any protrusions sticking out from the inside of the housings, these must be smoothed down with a file.
  11. Place the rubber dust boot provided over the cut end of the tube.
  12. Insert the KONI insert into the tube and begin to install the lower bolt and washers, it is recommended but not required that you also use thread locker. The bumps on the side of the KONI insert are an interference fit and will require some force to go in. The bolt at the center bottom of the housing should be able to draw the insert in but some blows with a soft face hammer may be required to get it started inside. A soft face hammer (plastic or rubber) should only be used.
  13. Torque the lower bolt to 75Nm or 55 FT.LBS. Slide the dust boot over the top of the cut tube.

Assembling the front struts

A) Koni front shock assembled into strut housing

B) OEM dust cover (P/N 20322AG00A, qty.1/side)

C) OEM top mount (P/N 20320AG00A, qty.1/side)

D) Nut & Lock-washer from Koni kit

E) OEM bump stop (P/N 20321AA201, qty.1/side)

F) OEM conical washer (P/N 20326AA000, qty.1/side)

G) OEM upper spring seat (P/N 20323AG00A, qty.1/side)

H) Front spring

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